The withdrawal suggested the possibility of a major turn in the six-week war — the collapse, at least for now, of Russia’s initial attempt to seize Kyiv, the Ukrainian capital, and the end of its hopes for the quick subjugation of the nation.Moscow has described the withdrawal as a tactical move to regroup and reposition its forces for a major push in the Donbas region of eastern Ukraine. While there are early indications that the military is following through on that plan, analysts say it cannot obscure the magnitude of the defeat.